engine replacement in 78 nautique

I have recently purchased a 78 nautique only to find out the engine is stuffed. The problem is I am located in Australia. The current engine is a PCM 351 and BW velvet drive.
I have gathered that these engines rotate opposite to a standard car engine and that is where my dillema lies. I cannot seem to locate a direct replacement so is it possible to swap it for a different motor such as a 351 Cleveland? These are pretty common motors here so they are pretty cheap which is important. Will the gearbox be ok running in reverse? i understand i will need to replace the prop, is there anything else other than the usual things? or am i better off trying to rebuild the existing motor?

Sorry for so many questions im just in a bit of a dilemma and dont want to spend a fortune to get it on the water!!

Thanks in advance!

so by switching the pump around does that mean the prop still spins the right way? or am i on the totally wrong track? were these engines bought out in anything else? at least the same block?

So far it looks like rebuilding the original motor im just a bit worried after reading other posts about getting seals and the crank reground the right way! what are the other concerns if i was to get it rebuilt?

Doogs,
Rebuilding the existing is by far your easiest and cheapest way to go. Just make sure you order the correct seals for that reverse engine and your crank will be fine as you just need to have it turned, and not worry about the rotation issue if keeping it the same. So, UNLESS WOODY OR SOMEONE AT CORRECT CRAFT SUGGESTS CHANGING THE ROTATION, DO NOT. They didn't make them that way to make it difficult on us down the road. The cost of the new prop alone is greater than the increased cost of rebuilding it rev. rotation as opposed to standard/automotive rotation. If there are parts you can't get over there, just let us know. Unfortunately, the Cleveland engines really didn't make it on the marine scene here. Good luck.          

Doogs
reidp is correct, rebuilding the existing reverse rotation engine is the cheapest and most rewarding option. The seals should be available direct from PCM also.

make sure you get a reverse rotation camshaft as well,and also the distributer gear is reverse rotation also.

So you're still considering an automotive rotation? Well, a Windsor's a Windsor in that your original engine is as typical as they get, but only as far as a base engine design is concerned, so your manifolds will swap just fine. But not knowing where your proposed engine is coming from, your starter must match the engine rotation as it's not bi-directional. The marine distributor/engine is set up for mechanical advance and not vacuum like the autos. To use your existing dist you must have the cam-drive gear changed for std. rotation. Some one else chime in to talk Doogs out of this....   And did anyone mention that it's highly probably that the boat will list to starboard when cruising down the outback rivers and lakes?     

ok some good and bad news the block was stuffed but the guy who is rebuilding it found another block. i did notice that the oil seal on the water pump side was one piece and had grooves cut into it does this mean that i need specific reverse rotation seals?